Kinetics of catalytic treatment of coking wastewater (COD, phenol and cyanide) using wet air oxidation

Coking wastewater (CWW) is known as a highly polluting effluent. This study deals with the degradation of pollutants in terms of COD, phenol and cyanide present in CWW using catalytic wet air oxidation (CWAO) process. CWAO was carried out in batch mode using various catalysts. The investigated operating parameters are initial pH (pH i ) 3–11, temperature (T) 100–160 °C, air partial pressure (p air) 2–6 MPa, catalyst mass loading (C w ) 2–5 g/L and treatment time (t R ) of 0–6 h. Among various catalysts, the copper chloride was proved to be best for degradation of pollutants. The optimum conditions were evaluated for the degradation of organic compounds as T 130 °C, p air 8.8 MPa, C w 3 g/L and t R = 6 h. The maximum percentage reduction of COD, phenol, and cyanide was achieved through experiment at T 160 °C, p air 12.2 MPa, C w 5 g/L and t R 6 h as 97.32%, 97.94% and 99.87%, respectively. The kinetics studies were also performed to evaluate the rate constant (k), and reaction order with respect to COD, phenol, CN, CW and p air.

Insights into the Kinetics Degradation of Bisphenol A by Catalytic Wet Air Oxidation with Metals Supported onto Carbon Nanospheres

Emerging pollutants are an increasing problem in wastewater globally. Bisphenol A (BPA) is one compound belonging to this group. This work proposes the study of the employment of several metal-supported (2 wt. %) carbon nanospheres (CNS) for BPA degradation by catalytic wet-air oxidation. Several techniques were used for the catalyst characterization: thermogravimetry, X-ray diffractometry (XRD), Fourier transformed infrared spectrometry (FTIR), determination of isoelectric point, elemental analysis, X-ray fluorescence (XRF), scanning electron microscopy (SEM), and N2 adsorption–desorption isotherms. Different loads of Ru in the catalyst were also tested for BPA degradation (1, 2, 5, 7, and 10%), being the first minimum value to achieve a conversion above 97% in 90 min 2 wt. % of Ru in the CNS-Ru catalyst. In the stability test with CNS-Ru and CNS-Pt, CNS-Pt demonstrated less activity and stability. Two potential models were proposed to adjust experimental data with CNS-Ru(2%) at different conditions of BPA initial concentration, catalyst mass, temperature, and pressure of the reaction. Both models showed a high determination coefficient (R2 > 0.98). Finally, the efficiency of CNS-Ru and CNS-Pt was tested in a real hospital wastewater matrix obtaining better results the CNS-Pt(2%) catalyst.